Since my last comment, an updated kernel arrived via Update Manager. Its changelog included the following:
* md: fix possible corruption of array metadata on shutdown. - LP: #992038 This seems possibly relevant. I updated, and have now rebooted several times. The RAID degradation is still happening, on every reboot. As before, the system runs just fine after I finish fixing up RAID. I am now keeping detailed notes on which partitions are being degraded. Since it takes me anywhere from fifteen minutes to several hours to accomplish each reboot and ensuing repair, and I have other things to do as well, it will be a while before meaningful statistics are accumulated. Further details I forgot to mention earlier: This is an AMD64 system with 8GB of ECC RAM. Have attached most recent dmesg. ** Attachment added: "dmesg.txt" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/990913/+attachment/3157872/+files/dmesg.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/990913 Title: RAID goes into degrade mode on every boot 12.04 LTS server To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/990913/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs